New to Blender. My simple scene has really long render times
I would recommend the following changes:


Remove the second render layer, because it doesn't contribute anything to the compositing result and doubles the render time.
Use Branched Path Tracing with high samples for the diffuse sub samples and mesh lights and low samples for everything else. This reduces the noise significantly.


If you would be switching to the most recent version of Blender you could also use Open Image Denoise, which can reduce the required samples significantly.